SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '737144ebe51d5688d906a3c7aad51db5d06959bccf8eb9857e47bbf5c7a2a3e7' 
  AND token = 'mKdXatCsostw6GuslVAaev/HegZpR2lc/vlHfQ4Zids=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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