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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '799195b2b023aa281b39325eeeb2d6ef9e8f8e15228caadc82e7da1b96c1efc3' 
  AND token = 'UheQuzv45+cUxiq3cMSl5xQf41nmOvCbxJ61+koicQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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