SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f7def092b359407f61e85f8428a1f58ce2699ee92fd2f59a69a7acbdfd73970' 
  AND token = 'y7uANb8ymziRGAuXjytIintDSTaKVAmPIwQjaY7sUAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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