SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2e11992504d448b45821a4009cae8a9a968f8c79315c5b0c3813b60da67b501' 
  AND token = 'I5IuSlSeXS0f+Wb23u/PbW8RK4ha0Ye2ZxzehCYiawc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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