SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c247c2596bc0c7296fa29a60aaaf43c93020ee7edec4090390051d379dece2b4' 
  AND token = 'UWBoZLRLZfVbfYdBqf9i0/9sxG8zRhd8ApllE/BRHNg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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