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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b68f8b35ada92d12c532aef26449587604f99e47694d3c6266c61c9d9a21ab9' 
  AND token = '9jMTsrt6dcyYbDsUxtPDrXP0HAZ+PXRshomvEMjUR4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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