SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3c4c2034e99524070c1763773df3ce9e856485fc626838e1a0e26472dc60b40' 
  AND token = 'O+ndlCksK8WkXUQC3aE+I4vPpXwKyVZX1aMXb/S0SOg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}