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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6b17227c7c14e40d5c4b66766d3cbe62d74fdc2679cc9f5ba43fd6d4c41e54c' 
  AND token = 'lMBmRhdTY/fpvPNWtareroL963BHJ4ygtk8vjGsFc3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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