SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4d1e299373c7f204d9ca272bc54ed4d791852aca770e2066af86e57a209a3b4' 
  AND token = 'vLBRkemDWniPMZ0iLSQqpIwEADJlNDxgo/VFZQ1oVhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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