SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'f8c4e8a7b2dca070252a116468fc695d8f414506cec7b48722be44ca8263b3a2' 
  AND token = 'VF7qi4diW/rKkXSRpQ4PNQzOtMMzCodWaauP+mrktxE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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