SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2b33d44500e3f65f870074fc913bdab205b15df5ef8588e70313b32b8abffe2' 
  AND token = 'MxnDzJ2Qly44hP/C1LMlUTjMqPfhj6wxKo9lzwFm+fM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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