SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd803f429561f1be9abf415cb213beb3e98bb0e1bea0886a90ceecc5dc99d4039' 
  AND token = '71g2aJr4KU/RHLSmS9meqASmt3WmcH01wA0e4Kw6Edo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}