SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '203811f55bf34fa2e9aed78447679b32d96b3bc0a73ca8c214c40807f293b999' 
  AND token = '6qa/DBcf23LteBZOBE2+OZxO8tQ1QIRRsVqJjNYsG1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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