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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7750d3681c6f3c1e5d57676ba81ca0d71c80c5b2dcdbb2f269355eea67c16dd6' 
  AND token = '6XRsTuDc/k8/c6EiVKzmCAx9f9IXvZc/uzWWywskYQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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