SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f50c2caea25ce330ba0db39638e248ab73fe697ed811ed312e6f18fb4b71618f' 
  AND token = 'NtXNaXskxOPipOA4+AvbBGzyPdxovQnepDYQmuYYkaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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