SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54d95a6541c890acc0b82212a78431f960951d3cb339cd0afa0c6c532937114a' 
  AND token = 'tbmcVnt1XQvdaJJq46yTZwMpCf2FGPksWLRFaHxtBzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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