SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '717ac74c708800c45a27220c18a2580e55b2c7b329cc3201c2282dae163695c8' 
  AND token = 'RzPNDOPFihy/nbDUHR2qaE6+6/inTFCV1CLv2ncr7Ek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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