SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fd57a2f6999226de918186250eee6f13ffe1d15ab17186db63d09152936a47f' 
  AND token = '1UAZTTR8IJJkMbWVnGpmYGnq3/PGhjWz04+vrNN3tck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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