SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '854c4df6061fe236417373e31e71230a430f874de439d9250c2d5f638b47607b' 
  AND token = 'KJ6ad1FQdPD1hO/ULuRVzhrvldN1YGevx2UHJQEU5/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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