SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '855ffb86eb4dc525c72e9a1b9b64a0655dd7a80c21b1b095e91908f2d4b3f96c' 
  AND token = 'piUgMS9O8z0Ds/UK2sQP12V2GGMPPHZ9eGhyoqlr5f0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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