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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b77a1bcb31b4fa7fc4e5e9fb9e19a9c424af9de6d2e50408d689b00874ce764c' 
  AND token = 'mhAFIMvPoL6T2oPh7eP7nXZ+KfuPZK2no+WJy6x/pKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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