SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b98773b0b958dd5575205381acaede47fd9ad2effc0c2ed57c4d9c82e9000f5e' 
  AND token = '+cQqqkJW1Xxou7XqanEayngvuQclTDVl+uMrhopNd30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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