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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6c4d4b4c6fcc5353937b4ba9450049d0e18d2fc21a53fdbb4962b2e2a0d564c3' 
  AND token = 'o2MEZnSJTlhmFR/AokM/MN7LqdshNYAvNQJM3N5zrK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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