SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20195fbe54b213407aaa918368023aeb6c4b7d092277c501da09d0abbd049422' 
  AND token = 'SLFLe72Lpv+w1p3H8FPwP5asfh9ctwShhrphSD8O12U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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