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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d8ceaab6160ef045c46c2522404aff957a96b023a109fbe6dc6f53e0e249da2' 
  AND token = 'DlxtLAQfXIVlAEF0siYH7Ys5OYIJ1Lmd5eQ8T+jYU2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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