SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26908b5795279808addc2dfc8ec2ead15d978fd1972ee0d16cad50004af63a01' 
  AND token = 'r/3Jq2Sf5RYp5HNDT+qKz1Nme1gZP9NgnzeW5hKdM7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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