SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '666c5d87191ea4431ab71e176368281fd5546fc6a11071eb98f5c052fccae14d' 
  AND token = 'Qg7RvSqqVUnAnxehoogT0uxVsldIn/1FqsHFt30SOeQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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