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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3d8cfa1ab4d41f23ae6dc1bd81c1a9c26d3dfb227239bbb0aeb6daf3a02ff7e' 
  AND token = 'm0zuZV0avCO8yklj7khCHaFwK/0imGrAs17+Hi3iTCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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