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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dadc8a4bd7606ed743fc733c67e7ed2f8d8047401b5ed9d5b1e42b575bcf4f33' 
  AND token = 'FA3rMCxmiyNzthvWlcc3n7cpz923rBWcuiymlCy+VQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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