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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a66c14625ecc1c3b26f7962f15469179e1c0bb8e484bd27378aa283c63a843b3' 
  AND token = 'Z+MTQUbAD7T1SZq0CMbODOrmfUnBewrCNY3OlcxKLIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}