SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0752bafafff7a853788391ba043337ad1457cc4d458cfb272a46a6ff25d3841' 
  AND token = '/cChcVugxscSizTgqVALAcf+ui5XZkqBJFiET3hAgOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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