SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fc543807080570148d4f8751ef0fbb01a1ab3beb3c31b70eb09f15defa69890b' 
  AND token = 'o0uUBHLhFDyv4I52QTZF0b5FVpX8DF1eiXw3ygkR+pg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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