SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '946ff44225bcc5475528de727847fc7a68dc71810f84fb338e86c17c4d0fd267' 
  AND token = 'MKGFtNku/FPMjaKHBSfsQJrUIfSuJZP+ui8BRwiyeyE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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