SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a78e1a0785ae61f49e9adc134a6513bf4927a4457964bb46b2c96fb46e93665' 
  AND token = '0fhen8+VEHuIq97lZe/DdhbTUXAdGr4XPYzUUv2NgOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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