SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '975e63dcf135f2caaed568eb4a09240c9b54fc18ad27c460892fff8bfa2f4660' 
  AND token = 'Hww+bIwkDW6xnDCTNNEKkXNFWBS1SgLLahb4KrkyBJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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