SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03dc25c602c823bea06c68721fbb4082e04616c41b4bdb2b84c6ddc96057a9a2' 
  AND token = 'fFcJAZ1AHsV3pMRR0UVBm73sz6FAOWZxH3CRuJWsETg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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