SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56dab328d8b9d946bb41c341553c91641cff22cbfa9d0175af65feb7d0466272' 
  AND token = 'Kc0hQFBOdsxdEIfq4QCR6CjUdcXerTAb7nT/rs2blNE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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