SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '41a2c6fb6b126778cee258ef6514fad5938101c892fc00f70711206eb11da18d' 
  AND token = '3za5GNFDdyMVCl+bwFGZoCgb3VFpYFhipIge0Jmjmg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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