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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8ac76dfba9045814d8a86b5a5ee7668b7bf744f7acf7c3944f5d6a7b3d93a5c' 
  AND token = 'uOUdQrVvHj7+PkReX2aiMYGzM7PELMfFMrf63oiF3I0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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