SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '755e7ff4932c60152d4fb4d62fafbe6e68988b32b3fbc73688b6b241267b1f66' 
  AND token = 'sv2B8FPPfvPXwqFF7AyGGPHnMpWbZ8tt8lhTCYY7GVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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