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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'db6dfb78d6801a01f4a3674891c62be3efb677c06fc2d3d5c9fce20cdeaa9ae3' 
  AND token = 'h1xzJaMD1FUIRRnkcCxPTg/XYwkU5bD0TkBHOewKI54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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