SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8406353df5c1797db2a3489bece2c0db090dd289737e69272b58d3e57a3ecf98' 
  AND token = 'QmVhpngjB1v4c+hut76lzydiyIILDWwuEF9iGwy7RFo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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