SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9924c53f611d5e1a042d51f90c456d26b548e507dfe68b7d0c5625336dae77dd' 
  AND token = 'xbJGPuOTa+91ebCF7zzhsEBAJWF2QIOtnc6JdM3yNnM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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