SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35c20a138bb2c794ee6e787e2610941ce4c0b88005d5334ee5492d03c7410aff' 
  AND token = 'uns6tguZfshAVZL4LjdtT3MnIlhdPt58JeOsNeTXTpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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