SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8bd8261720a9d9b258af6939e69a2a81aef3e5a1c17b9d4946048dc70f54be6d' 
  AND token = '5kSzAPOfrw5kWrkyJXpqE2Pd/2RNXgut2tjQm2FbkMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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