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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4309698f2f3e440daa1d2a210ee7bc327ba736b5f0ec91a10869dfc04914b03a' 
  AND token = 'Ca8D2sGiIgRkhz1Jbj7ooGlZ/Bd46fi6/0RJAHGVjb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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